Game Piece images from sheets

I’m wondering if I’m missing something… is there a way to extract single game piece images from sheets (so I’ve got a sheet with 10 cards on it, and I want to make 10 separate cards) within the VASSAL module, or should I use an external editor to do that before importing into VASSAL?

I’m thinking of using GIMP’s guillotine feature to do this…

Use external editor - Something like GIMP you mentioned is perfect for this